Frequency-control system



April 22 '1924. 1,490,958

- R. BowN FREQUENCY CONTROL, SYSTEM Filed Nov. 23. 1921 ,amw 0/0000(M000 5/0000 mlm (500000 1001; mmp500000- //tb%(.600 Ilia/10:11am

INVENTOR ATTOR N EY Patented Apr. 22, 1924.

UNITED STATES 1,490,955 PATENT OFFICE.

RALPH sown, or 'rnEEnoLn, NEW JERSEY, ASSIGNOB 'ro AMERICAN TELEPHONEAND "TELEGRAPH COMPANY, A CORPORATION ornnw YORK.

FREQUENCY-CONTROL SYSTEM.

Application filed November 23, 1921 Serial No. 517,280.

T all whom it may concern:

Be it known that I, RALPH BoWN, residing at' Freehold, .in the county ofMonmouth and Stateof New Jerse have in- I vented certainlmprovements inrequency- Control Systems, of which the followingis a specification.This invention relates to radio signaling and .more particularly toarrangements for controlling signaling frequencies used by differentstations. Theradio signaling, where a large number of signaling stationsare to signal simultaneously; it. is desirable thateach pairof 16communicating stations signal at one or more radio, f equencies,difierin from. the frequencies. \ised by all'other pairs ofcommunicatinglstationsin order to, acid interq ferencei (Furthermore,theyarious signal-r ing stations maybedivided up into groups orsystems,- depending upon the cooperation ofseveral interests controllingthe system. or group-. Since but one irequency spec;

- trum isavailable to all of the partie s inter.-.- 2b ested'f itisldesi ra ble. that the spectrum be dividednp and certain ranges.oifrequencies be assigned to each group. -The organizationoperating' agiven group ofstations then have available. for signaling as many' 80'channels .as can be included. within therange assigns and these channelsmay be individual channels fgr} individual signaling, staitions, oraplurality-of channelsmay be as signed. to a station for multiplexsignalingj 3 In order to'prevent the stations of a group fromoverlapping in their operation. the:

range ot fre uencies assigned. to another group, lt lsBSIIElblG'tl'lELl'i some means or ,method be provided for definitely.relating W the frequencies of the various groups with: reference to eachother so that a shifting of the bandof frequencies utilized by one groupwill be accompanied'by a corresponding;

shifting of the frequenciesutilized by other: groups. It has heretofore.been proposed to accomplish this result by generating at.

a master station one or moredundamental frequencies whichmay he radiatedto the itations of thevarious groups, or systems,- the various s1 nalingfrequencies to be used h the individual stations of the groups beingderived from the energyof the rev neived. fundamental- .frequency or.frequen- ;-cie-s hya process-of' a-mplification and f re-- qucncytranslation.

-suitable apparatus for -translating the mas- This method has theobvious disadvantage that the energy to be used for signaling at thevarious stations isv a-function of the energy received from the-mastercontrolling station. Consequently atany time the amount of energy to'beradiated5forsignalmg purposes by a givenstation'will do end upon the,amount off-energy radiated rom the master station andz- .upon the loss.=,of energy in transmission from thejmaster stationto thesignalingstation. In accordance with the resent invention it;.i s pro osed. togenerate t e energy-to be used for signaling at eachsignaling jstationso'that the amount of energy to .be used .forasig'nalin will beindependent of, the amount-Jo energy radiated at themasterstationuthefrequency of the energy-generated,however, being-con trolled anddetermined by the frequency radiated from the.masters tation.' In otherwords; the methodiis such that thecontrol; exercised by; thegmasterstation. is one of frequency;..-,on ly and gthe amplitude; of. the.energy. controlled;v entirely; by. -.-the local signaling station.

The" inyention. may:

; v =-now be moremfully understood -from the a following ;description:when read in connection with the accompany; ingdrawings; which-Figuredis. a sche-' matic. diagram; illustrating. broadly one metho of carryingout the inyention, Fig. 21. is-a diagram of a portion ofthe apparatusat: one of thesi aling .stationseschematically' indicated in ld i g-tl,and Fig. 3 isa series. ofcurves. illustrating the operation of the controlling apparatus. .1 T-

- 1' Referring to Fig.1; designates a-mas-. ter control station at whichapparatus mayo be provided to radiate.;-,afundamental .radiofrequency'ofsay-150,000 fcyples,"which;is to be picked up by the varioussignaling sta-E tions and translated into-.- the-particular radiofrequency usedfor intercommunication between, any pairof stations. Twopairs of intercommunicating stationsr1-2 and 3-4 are schematicallyillustrated in Fig. 1. each pairheing typicalaof a larger group and itbeing further understood that in actual practice more than-two stations;may intercommunicate at t is sarne frecpienc Each station may include anapparatus schematically indicated .by-R for receiving themes tercontrolling .frequenoy, together with ter controlling frequency into afrequency or frequencies suitable for the exercise of control overthe-particular frequency .to be locally generatedand usedfor-intercommun'ication. As shown schematically in Fig.- 1, separateapparatus maybe used iii-conjunction with the receiving apparatus R forcontrolling the frequency generated for the localtransmitter T andvthermal-receiver R. Where a heterodyne or homodyne system is notemployed hoiv'vei it 'ivill be understood that noappar atuslisnecessary. for

ergj of thedifi'reireefr'eduelfey ay be im firessed a cafe; device"which is sensitive to frquenqiel eages and jtlii 's dvicfm'ey be used togovem' the rreqaeny'ef 'theTf-loc'a1 generator.

Ifi'oi-derto ri dergtafid more ially'the naturef {cr che controlmechanism; 'r'ffeiiee may be had tathe appsrawsiunstret d"in Fig. 2, theapp'ziratusth olwn' in thisfi 'ure being typicalo'ffthe"ifichanisnidocated 'at and interconnecting mint-s lt; and orpoints R and B, so far as this mechanism is concerned 1 with] frequency"control. The.

antenna 10' of Figf'2j nia-y be nay Well 'lznown type'o'f receiving-ai-nter'ina 'a'ndlha 's' associated therewith a 11 0f it iell knowntype""for' selectingthekofitfH frequency radiated from the distant"master station. -="'I his 'fi1ter"may' be, for example, atuu edcircuitor 'ab'a nd filterof' theGa'jnpbell type.

VVhef e'the' frequenc'y to be'us'd in signaling 'difi'ers"quit'ematerially from the master frequencyit'is necessary to produce aharmonic of {the "ma's'ter'ifiequeiic'y'which will be closely relatedinfthefrequency-"spec trum to the freqi'i'e'ney which"it"isidesiied"togenerate. For this purpose the selected master frequencyfi's"impressediipen'fa harmonic producer-I2 of fill-knofixfty'pef For example, "it isnow well known that flthe distorting" action of a"racuuin tube-may be'us'e'tl' to piedu 'e'l mnoniejsbf a fundamental frequency applied tube,(le

sired harmonic may be selected by suitable selecting 'means.' Assumingthat the apparatus illustrated is to be used for the control of thesignaling frequency at the transmitter-T of station 1 the-harmonic pro 7liitifi appifatusllff through a transformer 1'52" l'iI modulatingapparatus as 'illu'stiaite 'd isof tli'e'duiilx vacuum tube typedisclosed in Carson Patent 1343307, fissu ed Ilii'n' 115 -1 920. Thelocal generator for sup- Tier" ireiuengy to transriiitte'i or receiver,as t "e' he, may comprise for examp le an oscillator of the i'xfellilfi'ioit ii' 'V'aE iiiiI'fi" e, se. fr.eqii'e'iicy isgebngreliaby'm tngof asiiitabh atljii's'tablciipacitv' C. Ai'coiinec-t-iorj 16 eiareoscillator O to the comrri'on path of the.

vae iurh .tubemiodulator s o 'that the ql 'eiicy 'siljiplied theoscillator 0 may with "the" harmonic frequency .d erived ffbin'fhe'iceived' 'iiiaster frequency. Aspecitil form of tiiiied circuitarrangemarge-meattam-pris ng ewe-sharply tuned c'i'rc u-i't l7 a'nr.l'18. "One'of' these ti1ned c ir-, dense-associated with the inputcircuit of vieuiiiff'tiib l9 and 'tlie olther With the irlp'ut'circuit-"oi i a'c'iiii'in'tube 20. The 'yacuurn-"tubes ie end'eo aroi'rhe'dtecmr type andjeafih' includes in its 'output circuit a winding21 or '22 'oiaselenoid arrangement foF'adj'usti'ng the condenser orcapacity C.

In tl-iiez 'seiasgumed, wlierleth' harmonic frequency is 500,000 c\'cles and the freqiie'ncy generated-b the oscillator 'O is 510,000 cjclesl', 2i beatfrequency of 10,000 cycles wiltappear in the outputcircuit of the modifier-3r M. The tuned circuits 1? and 18":11'6 "soadjusted that the resonance peak of thepnejWil-l correspond to :1treueen-c5 lower than 10,000 cycles and the resonance peak of the otherwill correspond td'ii"fiquncydii'gher than l0 .000"cycles. asil'liisfiat'ed by the cur'ves 23iand 24 of Fig. In these curves'the''v'ertical dotted line corresponds the normal beat frequen'oi of 10.000cycles and atthis' frcqiwncy the curves of the two tuned circuits' 17and 1S mferlap qiiallfi 'ti thgit the same amount of ci'ii'ient'wil'lbe' s'el c'te d into'each of these tundhfircl'iits, and hy fednseqeneethe same auiouiit of direct current-Twill flow in each of'th'ejc'oi-ls"21 'zi'n'df22f Under these circumsta'r'ic'es'"t'h' plunger of thefsolenoid will occupy an intermediate position and the capacity C will be setso that the desired frequency of 510,000 cycles will be generated by theoscillator and supplied over the circuit 25 to the radio transmitter orreceiver, as the case may be.

If, however, the master control frequency varies so thatits frequencybecomes lower for example, the harmonic frequency supplied bythemodulator M will be lower and the beat frequency appearing in the outputcireuitof the modulator-will be greater than 10,000 cycles. This willcause the current flowing through one or the other of the oscillator O.It will thus be seen that the automatic governing apparatus operates tomaintain afrequency difl'eren'cesubstantially constantso that I thefreq11'ency"'s1ipplied over the circuit'j25 'will vary a up and downasthejfundaniehtal frequency varies up and down; If, 'now,' 'similarapparatusbe; provided at each station itwjll be seen that thesignalingfrequencies generated will vary at allstations in thesame'directio'n atthe same time, and by proportionate-amounts.

It will be not'edjthat the'dontrol arrange ment described is of"such-character that thecontrol exercisedgovei'fthe condenser 'o'r" "caY pacity C is entirelyindependen iwf th'e amonntf 'ofenergy" ''received"by I the" I antenna" 10Lan'd is" proportionate to the yariation p'f the"master" frequency or "harmonic thereof" from the: predeterminedstandard; The energy locally generated is' therefore at" "all -tiniesquaiititatively controllable at the station.-

*In thepreviousdescription the operation ofii the apparatus has beendescribed for the case in which the incoming master frequency 1 changesand the 'freq1'1ency generated by the'j oscllla'tor'O is changedcorrespondingly. It 1 is "obvious; howev'en that if the j incomingmaster frequency remains cons-tant-andffor any reason thefrequency"ofthe oscillator 0' should vary, the capacity 'Cfwill be'ad jjusted 'to bring the fr'eque'ncybf the osci1 lator' back to normal asthe changed 'fre-" quency from the"'os"c illator 0 will pass through thecircuit 16 to beat with the master frequency in themodulator M.

It will be obvious that'the' general'prin ciples here disclosed may beembodied in many other organizations widely "different" from thoseillustrated without departing from the'spirit of the invention asdefined in the following claims.

What is claimed is:

1. ln a radio system in which a plurality of radio stations are dividedinto groups of inter-communicating stations, each group having assignedto it a definite frequency 7 range which shall not interfere with thefrequency range assigned to any other group, the method of controllingthe fre-' quencies used in the various groups for signaling, whichconsists in generating at a 7 master station a fundamental frequency,transmitting said frequency to the stations of the various groups,generating at said station energy to be used for signaling, andcontrolling: bythe fundamental frequency Bl) received at each stationthe frequency of the locally generated ener y without controlling theamplitude of t e energy.

2. In a radio system in which a lurality of radio stations are dividedinto 55 groups of intercommunicating stations, each group havingassigned to it a. definite frequency range which'sh'all not interferewith the frequency range assigned to any other group,'the method ofcontrolling the frequencies used in thevarious groups for signalingwhich consists in generating at', a master station'a fundamentalfrequency-, transmitting said frequency to the stations" of the variousgroups, deriving from the received fundamental frequency otherjfifequencies at the several stations,'-"generating atsa'id' stations!energy 'to' be used for signaling, and controlling 'by' means of thederived frequencies the frequency of the locally generatedenergyfwithont' control ling' thei'amplitude thereofm j 3. 'In a radiosystem in"'which" a plur'al-' ity" of fradio'" stations are divided intogroups i of interconimunicating stations, each group having assign'edftoit a definite frequencyf rangve which shall' not interfere with'fthe'frequency (range "assigned ft'o' any othei groum' the fmetho'd ofcontrolling the frequencies used in'the various gr'oup'sforsignalingyvhich consists' in generating at a In'a.'ster"station afundamental frequency. transmitting said frequency to the "stat ionsof-",the' various groups; generating-locally a freqfiency'tobe used'for's igpalin'g, produc- 116 ing a det'e'rminin frequency which is 1 a Qfunction of the difference 'het'weenthe fundamental" "frequency'{and thelocally generated frequency, and-controlling the frequency of, saidlocally generated'frequency 120 in accordancewith said determiningfreuency without controlling the amplitude ter'eoff'j f 4. The methodofpreventingrelative frequency changes between a plurality'of separateradio channels of con'im1.1nication involvinga plurality of radiostations. which consists in transmitting acontrol frequency to 'eac-h'oftheradio' swims: involved; generating at each station energy to be usedin no si -rnaling, and controlling the frequency of the locallygeneratedenergyin accordance with the control frequency withoutcontrolling the amplitude of the energy.

5, The method of preventing relative fre- 1 quency changes between aplurality of sepa amplitude, thereof. a

derivedrrfrequency Without. controllingrithe 6. The method ofpreventing-relativeifre i quency changps between a plurality; oflsepalrate; radiate anne'ls ofrcommunication volv'ingaa plurality ofz-radiostationsf-Ivhich consists in transmittinglwcontroltfreqnency toiea'chfof the radi stations.-inyo;lwed;; gencrating-'1- at; ea ch 1 radio-Station; a; local; quency; t'oebe; ?.usede;forssignaling,. producingtion vof-nthe difference between, the locally; generatedfrequency andthe; 'centroli; :,r-: q1 1e.11 y,.-,andv c ntrolling the! frequency;vlof= said locally; generated fr"equency- ,in accords ance with saiddetermining frequency withr.

out controlling they amplitude ;th er'eof:, 7; The method ofgfixingfrequency ref;- lation between a. plurality of non intercom municatingradio stationsqwhich cQnsists,in

transmitting toeach of saidstations a-cpntrol frequency-,i-generating'fat each station; energy to be used .in 'si nalin", and con trolling thefrequency of--the ally generated energy in accordance with-the,--.con-,

trol frequency without controlling theam plitude of the energy;

8. The method of fixing frequency relation between a plurality ofnonsintercommunicating radio stations whichconsistsjn transmitting toeach of said stations a con-' trol frequency, deriving at each radiotstae tion a frequency from the control frequency, generating at eachstation local energy to be used for signaling, and controllin thefrequency of said local energy in accor ance' with the derived frequencywithout controlling the amplitude thereof.

v9. The method of fixing frequencyrelation between a plurality ofnon-intercommunicating radio stations which consists in tr'ansmittingtoeach of said stations a con trol frequency, generatil-ig at each radio1-;.

tion a local frequency to be used for signal-' ing. producing 5 adetermining frequency which is a function ,of the difference between theloca-llygenerated frequency andthe con--- trol frequency, andcontrolling the fre--- quency of said locally generated frequency, inaccordance with said determining fregenerated! frequencyeto; produce a--difference frequency,-;-and controlling. by said difi'er ence frequency;,the frequency of: said :locally genenatedifrequehcy without controllingthe mplitude'thereof, 5-. .ff 1'1.{-;-lI;i1 :flraYdiosystentdnwvhich aplurality Qi radio) stationsmre I divided into T cups of:Qmrnunicatingdstations; eac hav gvass g' ed to iitl-iaidefini e q ncytangent-hit h shall-notintenferewith the. he. qiiencyemng z-as igneddtoan ,;o'therou he method 1%reontrallingietimafreqlgnci s in; *thfinfiifiql h groups for. sign i g, wh hmn s singenerating=at a-masterf's'taime-a (maamennaaquenm r nsmittin aidzinequeney tql-the stations-9fthe Various gr0upsgenerat n it-said ationenergy-'-= th ;b is d1 fesignml n' [and Whose/8 p tude: is independent-pf; e fundamental frequench-and .i Ql ztroll-ingaby the fundamental frequency (receivedat-each -station the fre qnency iofj the locallyjgenerated energy. 112.3 ln a radio system-m which a-gplur'ality ofr-adio stations-ate,divided into groups of rcemmuniaa ng i: sta iq "each g p havingassigned; .to; {it a" definite frequency ra gecwh ch shall not interferewith-thefrequency rangoA-assigned to anyother group, the-:methOd of--controlling the frequencies used in the various groups for signalingwhich consists -in generating at 4 a master stationa fundamentalfrequency, transmitting said frequencyto the stations of the variousgroups, deriving from the received fundamental frequency other-.frequencies alt-the several stations, generating atusa-id"stations-energy to'beused for signaling and whose amplitude isindependent of the fundamental frequency. and controlling by means ofthederived-frequencies the frequency of the locally generated energy-18J'I11 a radio system inwhichaplrwality of radio stations redividedinto groups of inter-communicating stations, each group haying'assignedto it a definite frequency range which shall not interfere with thefrequency range assigned to any other group, thejmethod ofcontrollingthe frequenoie'sused in the/various groups for signaling which consistsin generating at a master, station a fundamental frequency,transmitting-said frequency to the stations of the various groups,generating locally a frequency to be used for signaling and whoseamplitude is independent of the fundamental frequency, producing adeterminin frequency which is a function of the di erence between thefundamental frequency and the locally generated frequency, andcontrolling the frequency of said locally generated frequency inaccordance with said determining frequency.

14:. The method of preventing relative frequencychanges between aplurality of separate radio channels of communication involving aplurality of radio stations, which consists in transmitting a controlfrequency to each of the radio stations involved, generatin at eachstation energy to be used in signa ing and whose amplitude isindependent of the control frequency, and controlling the frequenc ofthe locally generated energy in accor ance with the control fre uency.

15. T e method of preventing relative frequency changes between aplurality of separate radio channels of communication involving aplurality of radio stations, which consists in transmitting a controlfreuency to each of the radio stations involved, derivin at each radiostation a frequency from t e control frequency, generating at eachstation local energy to .be used for signalingandwhose amplitude isindependent of the'icontrol frequency, and controlling the frequency ofsaid local energy in accordance with the derivedlfrequency. 16.The.'method of'pi'eventingrelative frequency changes 'jbetween-a.plurality of separatefradio channels} of ommunication involving aplurality Qor fadio stations,

which consists in transmitting a- 'fcontrol frequency to each of' thezradio stations involved, generating at each" radio station a localfrequency to be used for signaling and whose amplitude is independent ofthe control frequency 'j producing a determining frequencywhich is afunction of the difference between the locally generated frequen-*'="-',cy-' andi the control frequency, and controlling the frequency ofsaid locally generated frequency in accordance with said determining freuency.

17. e method of fixing frequency relation' between a plurality ofnon-intercommunicating radio stations which consists in transmitting toeach of said stations a control frequency, generating at each stationenergy to be used in signaling and whose amplitude is independent of thecontrol frequency, and controlling the frequency of the locallygenerated energy in accordance with the control frequency.

18. The method of fixing frequency re-. lation between a plurality ofnon-intercominunicating radio stations which consists in transmitting toeach of said stations a control frequency, deriving at each radiostation a frequency from the control frequency, generating at eachstation local energy to be used for signaling and whose amplitude isindependent of the control frequency, and controlling the frequency ofsaid local energy in accordance with the derived frequency.

19. The method of fixing frequency relation between a plurality ofnon-intercom mfunicating radio stations which consists in transmittingto each of said stations a control frequency, generating at each radiostation a local frequency to be used for signaling and whose amplitudeis independent of the control frequency, producing a determiningfrequency which is a function of the difference between the locallygener ated frequency and the control frequency,

and controlling the frequency of said locally generated frequency inaccordance with said determining fre uency.

20. The method 0 fixing the frequency relations between a plurality ofnon-inter-,

communicating radio stations which con- 'sists in transmitting to eachof said stations a control frequency, producing a harmonic of thecontrol frequency at each signaling station, locally generating at eachstation a frequency to be used for signaling and whose amplitude isindependent ofthe control frequency, modulating the harmonic frequencywith the locally generated fre quency to produce a difference frequency,and controlling by said difference frequen cy the frequency of saidlocally generated frequency.- i

In testimony whereof, I have signed my name to this specification this22nd day of November, 1921.

RALPH BOW'N.

